A composite shaft seal structure for a fluoroplastic centrifugal pump

Abstract

This utility model discloses a composite shaft seal structure for a fluoroplastic centrifugal pump, specifically relating to the field of centrifugal pumps. It includes a pump cover, a pump shaft, a first shaft sleeve, a second shaft sleeve, and a gland. A first sealing groove is formed at the left end of the inner wall of the pump cover's shaft hole, and a second sealing groove is formed at the right end of the inner wall of the pump cover's shaft hole. A stepped sealing cavity is formed between the first sealing groove, the gland, and the second shaft sleeve. The second shaft sleeve is fixedly installed on the left side of the outer surface of the pump shaft, and the first shaft sleeve is fixedly installed on the right side of the outer surface of the pump shaft. This fluoroplastic centrifugal pump composite shaft seal structure adds a stepped sealing cavity to the outside of the mechanical seal. The sealing cavity is filled with a composite sealing body composed of expanded polytetrafluoroethylene (ePTFE) sealing tape and modified PTFE-impregnated carbon fiber braided packing. When the mechanical seal fails due to wear or corrosion, the packing seal can still provide temporary leak-proof capability, significantly reducing the risk of sudden leakage, and is particularly suitable for highly corrosive, high-temperature, or particulate-containing media conditions.

Description

Technical Field

[0001] This utility model relates to the field of centrifugal pumps, and in particular to a composite shaft seal structure for a fluoroplastic centrifugal pump. Background Technology

[0002] Centrifugal pumps, as machines capable of transporting liquids, are widely used in daily life due to their excellent inherent characteristics and stable operation. Centrifugal pumps typically employ mechanical seals, which mainly consist of a rotating ring and a stationary ring. During the relative rotation of the rotating and stationary rings, a thin liquid film forms between them, achieving a sealing effect. However, the contact surface between the rotating and stationary rings wears rapidly under high-speed operation, lacks a long-term lubrication mechanism, and relies solely on mechanical seals, which are prone to failure under conditions of strong corrosion, high temperature, or particulate media, leading to an increased risk of leakage. Utility Model Content

[0003] The main objective of this invention is to provide a composite shaft seal structure for a fluoroplastic centrifugal pump, which can effectively solve the problems in the background art.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A composite shaft seal structure for a fluoroplastic centrifugal pump includes a pump cover, a pump shaft, a first shaft sleeve, a second shaft sleeve, and a pressure cap. A first sealing groove is formed at the left end of the inner wall of the pump cover's shaft hole, and a second sealing groove is formed at the right end of the inner wall of the pump cover's shaft hole. A stepped sealing cavity is formed between the first sealing groove, the pressure cap, and the second shaft sleeve. The second shaft sleeve is fixedly installed on the left side of the outer surface of the pump shaft, and the first shaft sleeve is fixedly installed on the right side of the outer surface of the pump shaft. The stepped sealing cavity is filled with a composite sealing body composed of expanded polytetrafluoroethylene (ePTFE) sealing tape and modified ePTFE-impregnated carbon fiber braided filler. The pressure cap is fixedly connected to the pump cover by bolts. From left to right, the outer surface of the first shaft sleeve is sequentially fitted with a first O-ring, a stationary ring, a rotating ring, a rotating ring sealing ring, a fixing plate, a spring, a rotating ring seat, and a retaining ring. The retaining ring is fixedly connected to the first shaft sleeve. The spring is embedded in the rotating ring seat. One end of the rotating ring seat is fitted onto the outside of the fixing plate, and one end of the rotating ring sealing ring is embedded inside the rotating ring.

[0005] Preferably, the expanded polytetrafluoroethylene sealing tape is spirally wound around the outside of the second bushing with a 30-60° oblique cut, and the number of winding layers is 2-3 turns.

[0006] Preferably, a second O-ring is embedded in the right end of the pressure cap.

[0007] Preferably, the outer surface of the second bushing is provided with a wear-resistant coating.

[0008] Preferably, the outer surface of the second bushing is fitted with a first extrusion ring, a disc spring, and a second extrusion ring. The disc spring is located between the first extrusion ring and the second extrusion ring. One end of the first extrusion ring abuts against the modified polytetrafluoroethylene impregnated carbon fiber braided filler, and the second extrusion ring abuts against the pressure cap.

[0009] Preferably, the moving ring is a laser-textured SiC ring with a micron-scale pit array on its surface, and the pits store lubricating grease.

[0010] Preferably, the stationary ring is nanodiamond-reinforced graphite.

[0011] Compared with the prior art, the present invention has the following beneficial effects: This utility model discloses a composite shaft seal structure for a fluoroplastic centrifugal pump. A stepped sealing cavity is added to the outside of the mechanical seal, and the cavity is filled with a composite seal body composed of expanded polytetrafluoroethylene (ePTFE) sealing strip and modified PTFE-impregnated carbon fiber braided packing. When the mechanical seal fails due to wear or corrosion, the packing seal can still provide temporary leak-proof capability, significantly reducing the risk of sudden leakage. It is particularly suitable for highly corrosive, high-temperature, or particulate-containing media conditions. Simultaneously, laser-textured SiC dynamic rings and nano-diamond-reinforced graphite stationary rings are used to reduce the friction coefficient and improve wear resistance and self-lubrication. A disc spring is added to link the first and second compression rings, automatically compensating for packing wear, maintaining the packing seal clamping force, and reducing manual maintenance. Attached Figure Description

[0012] Figure 1 is a schematic diagram of the overall structure of this utility model; Figure 2 is a partial structural schematic diagram of this utility model.

[0013] In the diagram: 1. Pump cover; 2. Pump shaft; 3. First shaft sleeve; 4. Second shaft sleeve; 5. Rotating ring seat; 6. Spring; 7. Fixing plate; 8. Rotating ring seal; 9. Rotating ring; 10. Stationary ring; 11. First O-ring; 12. Gland; 13. Expanded PTFE sealing strip; 14. Modified PTFE impregnated carbon fiber braided filler; 15. Second O-ring; 16. Wear-resistant coating; 17. First extrusion ring; 18. Disc spring; 19. Second extrusion ring; 101. First sealing groove; 102. Second sealing groove; 20. Retaining ring. Detailed Implementation

[0014] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0015] As shown in Figure 1-2, a composite shaft seal structure for a fluoroplastic centrifugal pump includes a pump cover 1, a pump shaft 2, a first shaft sleeve 3, a second shaft sleeve 4, and a pressure cap 12. A first sealing groove 101 is formed at the left end of the inner wall of the shaft hole of the pump cover 1, and a second sealing groove 102 is formed at the right end of the inner wall of the shaft hole of the pump cover 1. A stepped sealing cavity is formed between the first sealing groove 101, the pressure cap 12, and the second shaft sleeve 4. The second shaft sleeve 4 is fixedly installed on the left side of the outer surface of the pump shaft 2, and the first shaft sleeve 3 is fixedly installed on the right side of the outer surface of the pump shaft 2. The stepped sealing cavity is filled with a composite sealing body composed of expanded polytetrafluoroethylene (ePTFE) sealing tape 13 and modified ePTFE-impregnated carbon fiber braided filler 14. The pressure cap 12 is fixedly connected to the pump cover 1 by bolts. From left to right, the outer surface of the first shaft sleeve 3 is fitted with a first O-ring 11, a stationary ring 10, a moving ring 9, a moving ring sealing ring 8, a fixing plate 7, a spring 6, and a moving ring seat 5. The retaining ring 20 is fixedly connected to the first bushing 3. The spring 6 is embedded in the moving ring seat 5. One end of the moving ring seat 5 is sleeved on the outside of the fixed piece 7. One end of the moving ring sealing ring 8 is embedded in the inside of the moving ring 9.

[0016] The expanded polytetrafluoroethylene sealing tape 13 is spirally wound around the outside of the second bushing 4 with a 30-60° oblique cut, with 2-3 wrapping layers, to improve the sealing tape's fit and resistance to media penetration.

[0017] The right end of the pressure cap 12 is fitted with a second O-ring 15.

[0018] The outer surface of the second bushing 4 is provided with a wear-resistant coating 16.

[0019] The outer surface of the second bushing 4 is fitted with a first compression ring 17, a disc spring 18, and a second compression ring 19. The disc spring 18 is located between the first compression ring 17 and the second compression ring 19. One end of the first compression ring 17 abuts against the modified polytetrafluoroethylene impregnated carbon fiber braided filler 14, and the second compression ring 19 abuts against the gland 12. The disc spring 18 can automatically compensate for the sealing gap caused by the wear of the filler, maintain a constant sealing pressure, and reduce the frequency of manual adjustment and maintenance.

[0020] The moving ring 9 is a laser-textured SiC ring with a surface array of micron-sized pits. The pits in the array have a diameter of 40–60 μm, a depth of 8–12 μm, and a density of 200–300 pits / mm. 2 The recesses store grease, significantly reducing the coefficient of friction and improving self-lubrication, thus enhancing the dynamic ring 9. The sealing effect between the stationary ring 10 and the stationary ring 10 is achieved by the stationary ring 10 being made of nano-diamond reinforced graphite, which has both high wear resistance and chemical inertness, reducing frictional loss under high-speed operation, extending the sealing life, and adapting to frequent start-stop conditions.

[0021] The working principle of this utility model is as follows: The operator puts the first bushing 3 onto the rotating ring seat 5. The rotating ring seat 5 is equipped with a spring 6 and a fixing plate 7. One end of the fixing plate 7 is equipped with a rotating ring sealing ring 8 and a rotating ring 9. The stationary ring 10 is installed in the first sealing groove 101. The preload of the spring 6 is transmitted to the rotating ring 9 through the rotating ring seat 5 to ensure stable contact of the mechanical seal end face. A first O-ring 11 is provided between the stationary ring 10 and the second sealing groove 102 to perform the mechanical seal function. At the same time, on the other side of the pump cover 1, the expanded polytetrafluoroethylene sealing tape 13 is spirally wound around the outside of the second bushing 4 with a 30-60° oblique cut and filled into the bottom layer of the stepped sealing cavity. Then, the modified polytetrafluoroethylene impregnated carbon fiber braided filler 14 is filled into the second bushing 4 and the stepped sealing cavity. Then, the first extrusion ring 17, the disc spring 18 and the second extrusion ring 19 are installed sequentially from the inside to the outside. Finally, the pressure cover 12 and the pump cover 1 are connected by bolts. The fixed connection uses a composite seal consisting of expanded polytetrafluoroethylene sealing strip 13 and modified polytetrafluoroethylene impregnated carbon fiber braided packing 14 to provide secondary sealing for the gap between the pump cover 1 and the pump shaft 2. After the mechanical seal fails, the packing seal provides supplementary sealing. This invention improves the shaft sealing performance of the centrifugal pump by using a composite seal of mechanical seal and packing seal to seal the pump shaft 2.

[0022] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A fluoroplastic centrifugal pump composite shaft seal structure, characterized by: The pump includes a pump cover (1), a pump shaft (2), a first bushing (3), a second bushing (4), and a gland (12). The pump cover (1) has a first sealing groove (101) on the left end of the inner wall of the shaft hole and a second sealing groove (102) on the right end of the inner wall of the shaft hole. The first sealing groove (101) forms a stepped sealing cavity with the gland (12) and the second bushing (4). The second bushing (4) is fixedly installed on the left side of the outer surface of the pump shaft (2), and the first bushing (3) is fixedly installed on the right side of the outer surface of the pump shaft (2). The stepped sealing cavity is filled with expanded polytetrafluoroethylene sealing tape (13) and modified polytetrafluoroethylene. The composite sealing body is composed of ethylene-impregnated carbon fiber braided packing (14). The gland (12) is fixedly connected to the pump cover (1) by bolts. The outer surface of the first bushing (3) is fitted with a first O-ring (11), a stationary ring (10), a moving ring (9), a moving ring sealing ring (8), a fixing plate (7), a spring (6), a moving ring seat (5) and a retaining ring (20) from left to right. The retaining ring (20) is fixedly connected to the first bushing (3). The spring (6) is embedded in the moving ring seat (5). One end of the moving ring seat (5) is sleeved on the outside of the fixing plate (7). One end of the moving ring sealing ring (8) is embedded in the inside of the moving ring (9).

2. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The expanded polytetrafluoroethylene sealing tape (13) is spirally wound around the outside of the second bushing (4) with a 30-60° oblique cut, and the number of winding layers is 2-3 turns.

3. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The right end of the pressure cap (12) is embedded with a second O-ring (15).

4. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The outer surface of the second bushing (4) is provided with a wear-resistant coating (16).

5. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The outer surface of the second bushing (4) is fitted with a first extrusion ring (17), a disc spring (18), and a second extrusion ring (19). The disc spring (18) is located between the first extrusion ring (17) and the second extrusion ring (19). One end of the first extrusion ring (17) abuts against the modified polytetrafluoroethylene impregnated carbon fiber braided filler (14), and the second extrusion ring (19) abuts against the pressure cap (12).

6. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The moving ring (9) is a laser-textured SiC ring with a micron-scale pit array on its surface, and grease is stored in the pits.

7. The fluoroplastic centrifugal pump composite shaft seal structure of claim 1, wherein: The stationary ring (10) is nanodiamond-reinforced graphite.

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